補償電極於負型液晶垂直配向邊緣場驅動結構之研究

Abstract

本篇以垂直配向邊緣場效驅動(Vertical Alignment Fringe-Field Switching,VA-FFS)之液晶顯示器做為研究目標。近年來，液晶顯示器對高穿透率與良好顯示品質之需求日益提升，其中3D VA-FFS結構具備優良之穿透率及反應速度，並且於先前研究顯示，負型液晶相較於正型液晶穿透率又能進一步得到提升。然而，由於主電極間隙區域之局部電場分布不均，液晶分子仍存在偏轉不足之情形，容易形成局部低穿透率區域，進而影響整體光學表現。 為改善上述問題，本研究於三階3D VA-FFS結構中導入補償電極設計，藉由額外局部電場調控液晶分子排列行為，以改善主電極間隙區域之電場分布。首先探討十字形補償電極於不同配置方式下對液晶排列、電場分布及光學特性之影響，驗證補償電極對提升液晶偏轉能力及改善穿透率之可行性。 發現十字形補償電極雖然能有效改善局部區域之液晶排列與光學表現，但其補償電極配置位置容易受到主電極間距之參數限制，影響設計彈性。因此，本研究進一步提出環狀式補償電極結構，藉由固定補償電極與主電極之相對位置，提高結構設計自由度，進一步探討不同參數配置下之補償效果。 研究結果顯示，環狀式補償電極同樣具備改善主電極間隙區域之局部電場分布之能力，使液晶分子獲得較佳偏轉能力。此外，環狀式補償電極能同時於不同配置條件下維持良好之光學表現，解決了十字形補償電極因結構參數調整導致補償效果降低之問題，使補償效果不再完全受主電極間距所限制，驗證其作為三階3D VA-FFS結構優化方案之可行性，可作為後續相關結構設計與研究之參考。

This study focuses on liquid crystal displays based on Vertical Alignment Fringe-Field Switching (VA-FFS). In recent years, the demand for high transmittance and superior display performance has continued to increase. Among various liquid crystal display technologies, the three-level 3D VA-FFS structure exhibits advantages in both transmittance and response characteristics. Previous studies have also shown that negative liquid crystals can further improve transmittance compared with positive liquid crystals, demonstrating considerable potential for future applications. However, due to the non-uniform local electric field distribution in the electrode-gap regions, insufficient liquid crystal reorientation may still occur, resulting in localized low-transmittance areas and degradation of the overall optical performance. To address this issue, compensation electrodes were introduced into the three-level 3D VA-FFS structure. By generating additional local electric fields, the liquid crystal alignment can be further controlled, thereby improving the electric field distribution within the electrode-gap regions. First, a cross-shaped compensation electrode structure was investigated under different configurations to evaluate its effects on liquid crystal alignment, electric field distribution, and optical performance. The simulation results confirmed the feasibility of using compensation electrodes to enhance liquid crystal reorientation and improve transmittance. Although the cross-shaped compensation electrode effectively improved local liquid crystal alignment and optical performance, its position was strongly constrained by the electrode-gap parameter, resulting in limited design flexibility. Therefore, a ring-shaped compensation electrode structure was further proposed in this study. By introducing an additional design parameter, the relative position between the compensation electrode and the main electrode could be independently adjusted, providing greater structural flexibility and allowing further investigation of compensation effects under different configurations. The simulation results indicate that the ring-shaped compensation electrode possesses a similar capability to improve the local electric field distribution within the electrode-gap regions and enhance liquid crystal reorientation. Furthermore, the ring-shaped compensation electrode maintains favorable optical performance over a wider range of structural configurations, alleviating the reduction in compensation effectiveness caused by parameter variations in the cross-shaped design. As a result, the compensation effect is no longer strictly limited by the electrode-gap distance. These findings demonstrate the feasibility of employing ring-shaped compensation electrodes as an optimization approach for three-level 3D VA-FFS structures and provide useful references for future liquid crystal display design and related research.